Ann Thorac Surg 2004;77:464-469
© 2004 The Society of Thoracic Surgeons
Original article: cardiovascular
Late results of palliative atrial switch for transposition, ventricular septal defect, and pulmonary vascular obstructive disease
Harold M. Burkhart, MDa,
Joseph A. Dearani, MDa*,
William G. Williams, MDc,
Francisco J. Puga, MDa,
Douglas D. Mair, MDb,
David A. Ashburn, MDd,
Gary D. Webb, MDe,
Gordon K. Danielson, MDa
a Division of Cardiovascular Surgery, Mayo Clinic and Mayo Foundation, Rochester, Minnesota USA
b Division of Pediatric Cardiology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota, USA
c Division of Cardiovascular Surgery, Hospital for Sick Children, Toronto, Ontario, Canada
d Congenital Heart Surgeons Society, Hospital for Sick Children, Toronto, Ontario, Canada
e Toronto Congenital Cardiac Center for Adults, Toronto General Hospital, Toronto, Ontario, Canada
* Address reprint requests to Dr Dearani, Mayo Clinic, 200 First St SW, Rochester, MN 55905, USA.
e-mail: jdearani{at}mayo.edu
Presented at the Thirty-ninth Annual Meeting of The Society of Thoracic Surgeons, San Diego, CA, Jan 31–Feb 2, 2003.
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Abstract
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BACKGROUND: Palliative atrial switch (PAS) procedures that reroute pulmonary and systemic venous drainage and leave a ventricular septal defect (VSD) open have been used in the treatment of deeply cyanotic patients who have severe pulmonary vascular obstructive disease (PVOD). Palliative atrial switch is beneficial for patients with transposition of the great arteries or other complex lesions with VSD who show higher arterial oxygen saturation in the pulmonary artery than in the aorta (transposition hemodynamics/unfavorable streaming). We reviewed the early and late results of PAS (Mustard, n = 25; Senning, n = 3) in patients at two institutions.
METHODS: Between April 1965 and March 2000, PAS was performed in 28 cyanotic patients (18 male, 10 female). Median age was 10 years (range, 1 to 27). Mean preoperative pulmonary arterial pressure was 68 mm Hg (range, 30 to 121 mm Hg). Mean systemic arterial oxygen saturation was 65% (range, 47% to 80%). The majority of patients (95%) were in New York Heart Association (NYHA) functional class III or IV preoperatively.
RESULTS: Overall early mortality was 21%; for patients after 1972 (n = 23), the early mortality was 8.7%. Mean follow-up was 8.3 years (maximum 20). Mean postoperative systemic arterial oxygen saturation was increased significantly to 88% (p < 0.0001). Late survival for early survivors at 5, 10, and 15 years respectively was 84% (59%, 97%), 64% (39%, 88%), and 54% (15%, 72%). The NYHA functional class was significantly improved; 94% of late survivors (n = 17) were in functional class I or II (p = 0.002).
CONCLUSIONS: The PAS operation significantly improves systemic arterial oxygen saturation and quality of life in selected patients with transposition hemodynamics, VSD, and severe PVOD.
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Introduction
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In 1972 Lindesmith and associates were the first to report a series of patients with transposition of the great arteries, ventricular septal defect (VSD), and severe pulmonary vascular obstructive disease (PVOD) who underwent a palliative atrial switch operation (PAS) [1]. This operation consisted of a Mustard procedure to reroute pulmonary and systemic venous drainage while leaving the VSD open. The VSD was not closed because experience had shown that closure in such patients was associated with prohibitive early and late mortality [2]. Their results as well as those of others have shown improved early mortality and considerable relief of symptoms in deeply cyanotic patients with severe PVOD [2–5]. Indications for PAS have been extended to include patients having other complex congenital lesions with VSD and severe PVOD in whom oxygen saturations in the pulmonary artery are higher than in the aorta (transposition hemodynamics/unfavorable streaming). The purpose of this study was to examine the clinical course and late outcome of all patients who had PAS performed at our two institutions.
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Patients and methods
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Palliative atrial switch was performed in 28 patients between April 1965 and March 2000 at the Mayo Clinic in Rochester, Minnesota (n = 17), or the Hospital for Sick Children in Toronto, Ontario (n = 11). Early results of some of these patients have been reported previously [2, 3]. The medical records and related physician correspondence of these 28 patients were reviewed. Data obtained included patient demographics, preoperative functional status, operative procedure, preoperative and postoperative hemodynamics, early and late morbidity including any cardiovascular events or reoperations, late functional status, and survival. If the patient died the death certificate and medical records of the hospital and physician were reviewed. Institutional Review Board approval was obtained at both institutions for this retrospective review.
Eighteen patients were male and 10 were female. Median age at the time of PAS was 10 years (range, 1 to 27). Preoperative New York Heart Association (NYHA) functional class was available in 20 patients; the majority (95%) were in class III or IV. Fifteen patients received preoperative digoxin and 2 received diuretic therapy.
Anatomical diagnoses are shown in Table 1.
All patients had transposition hemodynamics/unfavorable streaming of blood resulting in higher oxygen saturations in the pulmonary artery than in the aorta. Cardiac catheterization data were available in the majority of patients. Preoperative pulmonary vascular resistance (PVR) ranged from 5 to 46 U · m2 (mean, 20; median, 19). Pulmonary vascular resistance on 100% oxygen inhalation ranged from 4.7 to 29 U · m2 (mean, 15; median, 17). The patient who had a PVR of 5 U · m2 had a hypoplastic right ventricle and straddling tricuspid valve that precluded VSD closure, and the PVR of 5 U · m2 was too high for a Fontan-type repair. Preoperative peak systolic pulmonary arterial pressure ranged from 30 to 121 mm Hg (mean, 68; median, 65). Oxygen saturation and hematocrit data are reported in Table 2.
Preoperatively the mean pulmonary arterial oxygen saturation was 18 percentage points higher than the mean systemic arterial saturation.
Nine patients had one or more palliative procedures (total 13) performed before PAS (Table 3).
Nineteen patients had no cardiac operations before their PAS.
Early mortality was defined as death occurring within 30 days of operation or at any time during the operative hospitalization. The probability of survival was estimated by the Kaplan-Meier method and 95% confidence intervals were calculated for each estimate [6]. All analyses were performed using SAS statistical software (SAS Institute, Cary, NC). Comparisons of preoperative and postoperative continuous variables were made using paired t tests. Changes in preoperative and postoperative NYHA classification were analyzed using the exact McNemar's test for discordant pairs. Values of p less than 0.05 were considered statistically significant.
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Results
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All operations were performed through a median sternotomy utilizing cardiopulmonary bypass. Twenty-five patients underwent a palliative Mustard procedure and 3 underwent a palliative Senning [7, 8]. Associated cardiac procedures included mitral valve replacement and tricuspid valve annuloplasty in 1 patient, superior vena cava patch angioplasty in 1, and patent ductus arteriosus closure in 1. Median cardiopulmonary bypass time was 95 minutes (range, 55 to 171). Aortic occlusion was utilized in 22 patients for a median time of 54 minutes (range, 3 to 97). Deep hypothermia with circulatory arrest was used in 6 patients for a median time of 53 minutes (range, 9 to 67).
Overall early mortality was 21% (6 patients). Early mortality for operations performed after 1972 was 8.7% (2 of 23 patients). Causes of early death were cardiac failure in 5 patients and mediastinal hemorrhage in 1.
Median hospital stay was 11 days (range, 7 to 68). Nonfatal morbidity in 11 patients included atrial arrhythmia (n = 5), pleural effusion requiring thoracentesis (n = 3), tracheostomy (n = 2), and chylothorax, pneumonia, transient ischemic attack, and reoperation for bleeding (n = 1 each). At late follow-up mean systemic arterial oxygen saturation increased 23 percentage points from 65% preoperatively to 88% postoperatively (p < 0.0001), and mean hematocrit decreased 19 percentage points from 64% to 45% (p < 0.0001; Table 2).
The mean follow-up for the 20 early survivors was 8.3 years with a maximum of 20 years. There were 10 known late deaths that occurred from 2.4 months to 18 years after operation. Causes of late death were sudden or arrhythmia in 4 patients, subsequent operation in 2, accidental drowning in 1, pulmonary embolism in 1, and unknown in 2. The 2 deaths related to reoperation occurred during a cesarean section in 1 patient and during VSD closure in the other (patient 6, Table 2). The latter patient developed progressive congestive heart failure 2 years after PAS and VSD closure was advised when a large left-to-right shunt (Qp/Qs of 2.3) was found on cardiac catheterization. The preoperative PVR of this patient is not known. Kaplan-Meier survival excluding early mortality was 84% (confidence interval [CI]: 59%, 97%), 64% (CI: 39%, 88%), and 54% (CI: 5%, 72%) at 5, 10, and 15 years respectively (Fig 1).
In a patient whose original PAS was performed at 4 years of age baffle stenosis developed and the patient underwent baffle revision 7 years later. He required a third operation 5 years after that for tricuspid valve replacement for tricuspid regurgitation and another baffle revision for baffle stenosis. He is alive and well 8 years after his last operation.
Of the 20 late survivors, NYHA functional class was available in 17. Functional class was significantly improved postoperatively: 5 patients were in class I, 11 in class II, and 1 in class III (p = 0.002; Fig 2).
Electrocardiographic data were available for review in 9 patients and all were in normal sinus rhythm. No patient received a permanent pacemaker at late follow-up.
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Fig 2. New York Heart Association (NYHA) functional class preoperatively (Preop) and postoperatively (Postop).
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Comment
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In the current era most patients with transposition of the great arteries and VSD avoid the development of PVOD because they have an early primary repair as infants. However for the occasional symptomatic cyanotic patient who does present with transposition of the great arteries, VSD, and severe PVOD, PAS should be considered. The indications for this operation have been extended to include patients with transposition of the great arteries, severe PVOD, and intact ventricular septum in whom a VSD is created at the time of PAS [4, 9] and patients with other complex congenital lesions with VSD, transposition hemodynamics, and severe PVOD [1, 10–12].
The intricate hemodynamic consequences of PAS have been described in detail by Mair and colleagues [2] There are substantial increases in effective pulmonary and systemic blood flows while the amount of desaturated systemic venous blood recirculating directly to the aorta decreases (Fig 3).
This results in a marked change in the relative proportions of fully saturated and desaturated blood reaching the aorta and leads to an increase in systemic arterial oxygen saturation along with a reduction in hematocrit. It is important to remember that PAS does not simply result in a reversal of the pulmonary arterial and aortic saturations; the postoperative systemic arterial saturation is usually higher than the preoperative pulmonary artery saturation (Table 2) [3]. However to achieve a substantial improvement the preoperative pulmonary arterial oxygen saturation should be at least 5 to 10 percentage points higher than systemic arterial saturation.
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Fig 3. (A) The anatomy of transposition hemodynamics with unfavorable streaming. The desaturated systemic blood (blue arrows) predominantly supplies the aorta whereas the more saturated blood (red arrows) predominantly supplies the pulmonary artery. Some mixing occurs at the level of the ventricular septal defect. (B) The hemodynamic results of the palliative atrial switch. After rerouting the systemic and pulmonary venous flow at the atrial level, the amount of saturated blood substantially increases in the aorta (red arrows). Some mixing occurs at the level of the ventricular septal defect. (Ao = aorta; IVC = inferior vena cava; LA = left atrium; LV = left ventricle; PA = pulmonary artery; PV = pulmonary veins; RA = right atrium; RV = right ventricle; SVC = superior vena cava.)
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A careful cardiac catheterization is essential for assessing any patient being considered for PAS. In addition to accurate measurement of pressures and saturations in the cardiac chambers and great arteries and calculations of blood flow in the pulmonary and systemic circuits, observations of any changes in these variables during 100% oxygen or nitric oxide inhalation are important. The definition of what constitutes "severe" PVOD is somewhat arbitrary. We have generally considered PVR to be severe when it is 10 to 12 U · m2 or greater. At that level advanced Heath-Edwards changes are usually present, indicating irreversible PVOD [13]. The range of PVR from 8 to 10 U · m2 is borderline; in some instances lung biopsy may be helpful. If the patient is only 1 or 2 years old and there has been a good reduction in PVR with 100% oxygen inhalation we would consider an atrial switch with VSD closure. Alternatively if the patient is older or has had a poor response to 100% oxygen we would favor a PAS. If the VSD is closed in a borderline candidate for atrial switch and hemodynamics are suboptimal after the patient is weaned from cardiopulmonary bypass, bypass can be reinstituted and a hole can be placed in the VSD patch thereby creating a PAS. Pulmonary vascular resistance less than 8 U · m2 may result in an unacceptable left-to-right shunt and ventricular failure after PAS. Although the preoperative PVR is not known, this situation probably occurred in the one patient early in this series who required reoperation for VSD closure because of congestive heart failure and a 2.3:1 left-to-right shunt.
Our institutions have performed PAS in 28 patients in order to improve the quality of life in these severely symptomatic, cyanotic patients. The significant mean increase of 23 percentage points in systemic arterial oxygen saturation (p < 0.0001), the significant drop in mean hematocrit (p < 0.0001), and the improvement by the vast majority of patients from NYHA functional class III and IV to class I and II attest to the success of this palliative operation. Others have reported increased systemic arterial saturations as well as decreased symptoms [4, 5, 9–12]. Sagin-Saylam and Somerville [5] reported 15- to 20-year follow-up in 10 patients undergoing PAS. In addition to improved saturations they noted only 1 patient in whom developed biventricular failure. They found evidence of some residual exercise limitations although overall quality of life was improved.
It is interesting to note that severely debilitated patients surviving PAS not only had a better quality of life but also had reasonable late survival. A 15-year survival rate of 54% would appear to be good given the poor condition of the patients preoperatively. It is also encouraging to see some patients with 20-year follow-up in this report as well as others [5].
The arterial switch procedure has become the operation of choice during the neonatal period for management of transposition of the great arteries with or without VSD. At least two case reports now exist of its application (leaving the VSD open) in the setting of late presentation pulmonary hypertension and PVOD [14, 15]. A palliative arterial switch has some potential advantages over PAS especially regarding avoidance of late atrial arrhythmias and baffle obstruction but late results in this setting are not yet available. Both procedures are valid and effective; at the present time the decision regarding which to perform is made according to the individual surgeon's experience and preference.
In summary PAS can be performed with a current mortality of less than 9% in selected patients with transposition hemodynamics and severe PVOD. Significant improvements in systemic arterial saturation as well as quality of life can be expected.
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Discussion
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DR TOM R. KARL (San Francisco, CA): Have you extended this procedure to include patients with intact septum, performing atrial switch combined with creation of a VSD?
DR BURKHART: We haven't, but this is a valid concept. I am aware of the largest experience being reported from Great Ormond Street where palliative atrial switch combined with creation of a VSD was performed in 7 of 41 patients.
DR RALPH S. MOSCA (New York, NY): You mentioned that in a carefully selected subgroup of patients the palliative atrial switch procedure can certainly be helpful, improving quality of life and leading to higher systemic arterial oxygen saturations. Can you give us a little bit more information concerning selection criteria for these patients? Is there any age at which this becomes too much of an operation? Is there a certain physiology or associated diseases that would deter you from attempting this operation?
DR BURKHART: As with any other major palliative procedure, operation would probably not be undertaken if the patient has important comorbidities, which would significantly shorten life expectancy. The two major issues are to be sure that the patient has severe elevation of pulmonary vascular resistance with irreversible pulmonary vascular obstructive disease and that the preoperative pulmonary arterial oxygen saturation is at least 5 to 10 percentage points higher than systemic arterial saturation. If the pulmonary vascular obstructive disease is not irreversible, a large left-to-right shunt and heart failure may occur, and if the saturation difference is less than 5 to 10 points, the patient may not have substantial improvement. Accurate determination of pulmonary vascular resistance and reversibility of pulmonary vascular obstructive disease can be difficult; cardiac catheterization including oxygen or nitric oxide breathing is essential, and lung biopsy may be helpful.
DR MOSCA: How about age? Was age a factor at all in your decision-making and how did it effect outcomes?
DR BURKHART: Age was not a factor; the oldest patient was 27 years old.
DR ERIC L. CEITHAML (Jacksonville, FL): Since there was a significant incidence of arrhythmias, some of which were lethal, did you consider putting any of these patients on antiarrhythmic agents routinely or pacemaker therapy?
DR BURKHART: Known atrial and ventricular arrhythmias are treated with antiarrhythmic agents in the same way as patients with other cardiac diagnoses. It is true that sudden death is a common mode of death for patients with severe pulmonary vascular obstructive disease. However, we are not aware of any evidence that prophylactic antiarrhythmic agents are effective in preventing sudden death, and all antiarrhythmics have serious side effects. Implantable cardioverter defibrillators have proven to be effective in preventing sudden death in patients with hypertrophic cardiomyopathy who are in a high-risk status, and they may also prove to have a role in patients with severe pulmonary vascular obstructive disease.
DR PETER B. MANNING (Cincinnati, OH): I recognize that this series spans a long time period and particularly in more recent years, was there any thought to using a palliative arterial rather than an atrial switch? I echo the concerns that half of your deaths were due to arrhythmias and the incidence of arrhythmia problems late after atrial switch is far higher than after arterial switch.
DR BURKHART: I'm aware of a few palliative arterial switch case reports in the literature, and we have done a few at Mayo and Toronto. Both are clearly effective but it is not clear which will prove to be the best in the long run.
It is not known whether late sudden death in these patients is due principally to atrial or to ventricular arrhythmias. However, it seems likely that most are ventricular in origin, similar to those associated with severe combined right and left ventricular hypertrophy in patients with other cardiac diagnoses.
At the present time, the decision regarding which switch to perform is made according to the individual surgeon's experience and preference.
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References
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Abstract
Introduction
